The City of Lake Stevens' Parks and Recreation runs this course since it is in a city park. I don't expect there would be a problem with you having a tournament there as long as you don't want to shut down the course to other users that day. If you did want to be the only ones on the course, you will need to get a park use permit, insurance, and have the players sign waivers. With 20-40 players, I would suggest just showing up and having your tourney.

I will PM you with some other information that should help you. Let me know if some of the locals can help you out in any way.

Comment

Put up a small notice near hole #1 on the day of the tourney stating that your organization is having a tournament that day and to please give courtesy & priority to the tournament players. This may help a little.